Pulse based signal debugger

durations.cpp

/*

  This is useful for debugging systems that use low/high durations for communicating digital information. 
  I wrote this specific one for figuring out a wireless temperature/humidity gauge, thus to the 352+1

*/

#include <iostream>
#include <time.h>
#include <string.h>
#include <wiringPi.h>

using namespace std;

#define MESSAGE_LENGTH 353 // How long is our transmission? (Bits * 2) Consider adding 1 for the  trailing quiet time
#define SHORT_FAIL 200 // Durations less than this are considered noise, we reset if we hit noise

static int durations[MESSAGE_LENGTH];

void handleInterrupt() {
 
  static unsigned int duration;
  static unsigned int changeCount;
  static unsigned long lastTime;

  long time = micros();
  duration = time - lastTime;

  if (changeCount >= MESSAGE_LENGTH || duration < SHORT_FAIL) { 
    changeCount = 0;

    // Something of a sanity check, really no element should be 0, but we're ok with it for debugging
    if (durations[MESSAGE_LENGTH/2] != 0) {
      cout << '\n' << '\n';
      for (int i=0; i < MESSAGE_LENGTH; i=i++) {
        cout << durations[i] << " ";
      }
      cout << endl;
    }

    // 0 the array - quickly
    memset(durations, 0, sizeof(durations));

  } else {
    //store duration
    durations[changeCount++] = duration;
  }

  lastTime = time;  
}

int main(void) {
  if(wiringPiSetup() == -1)
       return 0;

   // Trip interrupt on rising and falling edges
  if ( wiringPiISR (1, INT_EDGE_BOTH, &handleInterrupt) < 0 ) {
      return 1;
  }

  // Keep it running
  while(true);
}